Machine productivity, particularly those performing tasks at a construction or forestry worksite, requires accurate operator control of the machine's work implement. This includes the position and trajectory of the work implement while performing an operation. Many conventional machines utilize automation to control the movement of the work implement in the X, Y, and Z directions. In other words, certain applications may augment operator inputs with automation and closed loop controls.
Conventional construction and forestry machine systems, such as a grade control for a bulldozer or dig depth control for an excavator and backhoe, may only include on-board sensors, such as inclinometers and potentiometers, to establish and control kinematic movement. More recent conventional control systems may use both an on-board and global referencing hardware such as a laser or global-positioning sensor (GPS). In some instances, these systems can provide sufficient precision, e.g., within a few inches, to perform a task. However, there are several factors that limit the accuracy and precision of position, trajectory, velocity, etc. of these systems such as joint wear, sensor accuracy and resolution, sensor mounting tolerances, oil compression, static and dynamic structural deflection, linkage dimensional tolerances, loss of line-of-sight with a global reference device, soil or supporting material deformation, and large-scale machine movement (e.g., during transport or repositioning).
Therefore, it would be desirable to provide a method and control system to achieve greater accuracy and precision of movement of an end effector or work implement coupled to a machine. It is further desirable to provide such a method and control system that can overcome or reduce the effects of the factors noted above that limit the accuracy and precision of conventional control systems. In addition, it would be desirable for a machine to be able to achieve digital or offline programmability and accuracy in order to perform functions typically reserved for high precision robots and rigid gantry cranes.